How to Choose a Backpack for Hiking | Volume, Fit & Frame Rules

Buying the wrong pack ruins a good trail day: too big forces overpacking, too small leaves gear strapped outside, poor fit puts weight on shoulders instead of hips. Selection comes down to three decisions in order: volume, fit, and frame type. Here’s how each works.

Volume: Match the Liters to Your Trip

General ranges by trip type, with common sweet spots noted:

• Day hikes: 18–30 L. A 25-liter pack covers a full day with food, water, layers, and first-aid kit. Over 30 L is unnecessary weight for a single day.
• Weekend trips (2–3 days): 40–55 L. A 50-liter handles three-season kit plus food and water. Keep loads under 25 lbs for comfort.
• Week-long trips (5–7 days): 55–70 L. Most hikers land at 60–65 L with resupply every few days.
• Extended treks (7+ days) or winter: 70–90 L. Winter adds bulk for sleeping bag, extra layers, and four-season tent. Carry capacity climbs to 40–70 lbs.
• Remote expeditions: 60–120 L. For trips without resupply or technical mountaineering with bulky gear.

The common error is buying too large. A bigger pack encourages overpacking, adds dead weight, and makes loads harder to stabilize. REI’s backpack buying guide notes most three-season kits stay under 20 lbs, so 50–60 liters works for most hikers.

Fit: Measure Torso Length, Not Height

Backpacks are sized by torso length and hip circumference—height alone tells nothing. Two hikers at 5’10” can need different sizes. Measure yours:

Measure your torso: Find the C7 vertebra (large bony lump at base of neck). Locate top of hip bones (iliac crest), find the point on your spine level with that line. Someone measures distance between C7 and that lumbar point in inches. That’s your torso length—compare to the manufacturer’s sizing chart.

Measure your hips: Wrap tape at top of hip crests over whatever layers you expect on trail—thick fleece and rain jacket change the measurement significantly. The hip belt must accommodate that range without cutting off circulation when cinched.

Check fit in-store with weight: Load pack with 15–20 lbs. Cinch waist belt just above hip bones, tighten shoulder and load-lifter straps. Weight should land on hips, not shoulders. Check for gap between pack and shoulders (suspension too long) or pressure on top of shoulders (too short). Load-lifter straps should sit at roughly a 45-degree angle; under 30 or over 60 degrees can cause neck strain or poor load transfer.

If buying online without trying packs, read our tested roundup of the best backpacks for hiking and travel to narrow options. Most manufacturers publish online fit guides based on torso measurements.

Frame Type and Load Capacity

The frame determines how much weight the pack can handle and where it sits.

Internal frame packs are mandatory for any load over 15–20 lbs. They transfer weight from shoulders to hip belt, which should carry 75–80% of total load. Standard internal frame packs handle 20–40 lbs comfortably; expedition models manage 40–70+ lbs. Healthy adult hikers typically carry 35–40% of body weight; experienced hikers push to 40–50%.

Ultralight (UL) packs cut weight with thinner fabric and minimal frames (Dyneema composite fabric common at high end). They typically handle 10–30 lbs max. Packing 40 lbs risks frame collapse, fabric tears, and discomfort. Reserve for trips where total pack weight stays under 25 lbs.

For fabric durability, look for 400 denier or higher on main body and bottom panel. A 50–60 liter pack weighing around 4 lbs is practical middle ground—durable for years, light enough for most hikers, sized for trips most people actually take.

FAQs

Can I use a day pack for a weekend trip?

Only if you can fit gear into 30 liters or less. Most weekend kits with tent, sleeping bag, pad, stove, and food need 40–50 liters. Strapping gear outside is unstable and shifts weight to shoulders.

What happens if my hip belt is too small?

A tight hip belt restricts circulation and transfers weight upward to shoulders. The belt should sit above hip bones, snug without digging in. Many packs offer women’s-specific belts.

Is a heavier pack always more durable?

Not necessarily. A 400-denier nylon pack with solid internal frame outlasts a 100-denier ultralight, but a 6-pound expedition pack is overkill for weekends. Match durability to use frequency, not weight alone.